Here I'm going to focus on the URI records and their possibilities to perform actions in NFC capable mobile phones when reading this type of tags. The URI specification says that these are the supported schemes:

I'm going to lay aside PDF files and malware to write a simple script to control friends and followers on Twitter. We use to have a lot of them and it's difficult to know if our friends haven't written some time ago or our followers have left. But we can use one of the multiple modules (talking about Python) to communicate with the Twitter API and solve this task. I've chosen Tweepy because I think it's very simple and well documented. What we want to obtain from Twitter is: